This invention relates in general to ramjet exhaust nozzles and more particularly to variable ramjet exhaust nozzles.
It is recognized that ramjet exhaust nozzle sized for boost take off speed is inherently inefficient at cruise speed. It is also recognized that if the nozzle exit area can be varied to match operating conditions, fuel economy and thus the range of the missile can be extended. These operating conditions include not only climb and cruise but also low level flight after descent.
There are a number of prior art patents directed to variable exhaust nozzles. Reference is made to the U.S. Pat. No. 4,049,199 to Nightingale, No. 3,040,517 to Ryden et al, No. 3,229,457 to Rowe et al and No. 3,079,752 to Thielman.
The Nightingale nozzle discloses master and slave pedals for varying the area of a gas turbine exhaust nozzle but none of the pedals are jetisonable for low level flight after descent.
The Ryden et al rocket nozzle provides a booster nozzle for climbing conditions which is released after serving its useful function.
The Rowe et al rocket nozzle changes shape during ascent of the rocket to a high altitude and means are shown for actuating the adjustment means during this performance but no means is provided for changing the rocket upon descent and low level conditions.
The Thielman nozzle provides for variable expansion of the exhaust nozzle by means of a plurality of concentric rings which are jetisoned when the rocket reaches the end of its climb.
There are, of course, a number of other prior art patents directed to this subject matter in addition to the foregoing including the U.S. Patent to Harrison No. 3,329,089 having a booster nozzle which is releasable from the vehicle and discloses a means for accomplishing this release and the U.S. Pat. No. 3,441,221 to Naud et al which like Nightingale utilizes flaps for varying a propulsion nozzle together with actuators for moving the flaps.
However, none of the foregoing meet the needs of a ramjet propelled missile by providing a large exhaust nozzle area for the missile climb to cruise altitude, reduces the exit area for better fuel economy for cruise and descent by extending heat resistant blocks into the exit area and again increases the exit area by jetisoning the heat resistant blocks for high speed low level run in.
Accordingly it is an object of this invention to provide the efficiency of the ramjet powered missile by providing a large exhaust nozzle exit area for missile climb to cruise altitude, reduce the exit area for better fuel economy for cruise and descent by heat resistant blocks into the exit area and again increase the exit area by jetisoning the heat resistant blocks for high speed sea level run-in.